What happens if you shake polyurethane

It came out great. The first coat on the top looked good too. But large bubbles formed in the second coat about 10 minutes after I applied it. So I sanded them out and brushed on a new coat.

Same problem! What should I do differently? Nobody wants to do all the work of refinishing and end up with bubbles in the finish. If it says don't shake, best do as you're told. I have been told that it isn't so much that you get bubbles as Matt said but that the bubbles become much smaller and more of them when shaken, making them more difficult to brush out and before they dry, or set.

It is more of a problem with gloss poly because it can make the finish look cloudy. I think it is the same with varnish and shellac. Bubbles are the issue, if you don't use a brush. From my personal experience, i have had bubbles either way. It has been true in my experience that if you lightly brush back the bubbles can go away.

I have also lightly run across the surface with Mineral Spirits to dissolve the bubbles, and that works. Overall I wouldn't choose to shake an oil based poly, because it creates more bubbles than you'd want, but there are ways around it.

To get the best results, just follow the directions on the can. I can't tell you how many times i've explained what to do to get the best results from a product, and customers don't listen, and they come back and say "this product didn't work". Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why shouldn't I shake my can of polyurethane? Ask Question. Asked 5 years, 11 months ago. Active 10 months ago. Viewed 11k times. Barring spilling the product all over the place; what am I risking if I shake the can?

Improve this question. FreeMan 4, 16 16 silver badges 35 35 bronze badges. Matt Matt Should the title be Why can't I or should it be Why shouldn't I? It's a fairly important semantical difference, I feel.

I for one have never had a problem shaking cans of finish. You might if you slather it on thick, but bubbles basically cease to be a problem the thinner you go. Why cant you, because you do not have any thumbs? Perhaps it should say should — Matt. Add a comment. Active Oldest Votes. Try to avoid slathering the polyurethane on your project especially on vertical parts because it will most likely leave drip marks that you will need to sand out later.

This video does a fantastic job of showing you exactly how to apply polyurethane using a foam brush for a smooth finish. Once you have your polyurethane applied evenly to your entire project, you can move onto the next step. The next step to getting rid of polyurethane bubbles and avoiding making them again is to let the polyurethane dry in a dust-free and bug-free environment.

This probably goes without saying, but if foreign objects get in your smooth finish, they could create bubbles or mess up your beautiful finish. It has a dry time of 4 hours before your project can be recoated. With a minimum of only two coats needing applied, you can have all coats of polyurethane applied in one day so it dry and be ready for use the next day!

I recommend choosing a day when you can apply the topcoat in your garage and leave the door shut for several hours at a time. The last step to getting rid of polyurethane bubbles and avoiding making them again is to apply at least 2 coats to your project. On the can, it recommends 3 coats of polyurethane, but the minimum is 2 coats. The reason why you want more coats of polyurethane is that every coat makes your project finish smoother. And every additional coat adds one more layer of protection.

That is more crucial for projects that might take a beating like tables or chairs or hardwood floors. Also, if you lightly sand with grit sandpaper between coats , you can get rid of any tiny bubbles or imperfections before adding another coat of polyurethane, which will give your project an even smoother finish. With only one coat of polyurethane, I think it makes the wood look cloudy and rough. Your wood should look beautiful with a professional finish!